X-ray CT scanner with graphical setting of beam thickness

Abstract

An X-ray CT scanner includes an X-ray tube which irradiates an object, a variable X-ray limiting device which limits the X-ray beam thickness, an X-ray detector which detects X rays transmitted through the object and has a plurality of detecting elements arrayed in a matrix manner, a storing unit which stores a plurality of calibration data files corresponding to a plurality of beam thicknesses, a correcting unit which corrects an output from the X-ray detector on the basis of at least one calibration data file read out from the storing unit, a reconstructing unit which reconstructs image data concerning the object on the basis of an output from the correcting unit, and a control unit which controls the variable X-ray limiting device to change the beam thickness of the X rays, independently of the beam thicknesses to which the calibration data files stored correspond.

1. An X-ray CT scanner for reconstructing a CT image of a subject, comprising:
 an X-ray source configured to emit an X-ray beam; 
 an X-ray detector having a plurality of detecting elements and configured to detect X-rays transmitted through the subject; 
 a reconstructing unit configured to reconstruct the CT image based on an output of the X-ray detector; 
 a determining unit configured to allow a user to set a thickness of the X-ray beam to an arbitrary integral multiple of a pitch of the detecting elements, as measured in a body axis direction of the subject, by graphically manipulating a frame representing the ends of the X-ray beam; 
 a control unit configured to generate a calibration data file used to correct projection data obtained using the set X-ray beam thickness, from stored calibration data corresponding to predetermined X-ray beam thicknesses other than the set X-ray beam thickness; and 
 a display unit configured to display a scanogram based on the reconstructed CT image, and to graphically display on the scanogram, the frame representing the ends of the X-ray beam set by the determining unit. 
 
     
     
       2. The scanner according to  claim 1 , wherein the display unit is configured to display, on the scanogram, information regarding a scanning range covered by a helical scan. 
     
     
       3. The scanner according to  claim 1 , wherein the display unit is configured to display a cursor indicating a center of an X-ray beam and a cursor indicating ends of an X-ray beam. 
     
     
       4. The X-ray CT scanner of  claim 1 , wherein the control unit is configured to generate the calibration data file by interpolation using the stored calibration data and the set X-ray beam thickness. 
     
     
       5. The X-ray CT scanner of  claim 1 , wherein the control unit is configured to generate the calibration data file by extrapolation using the stored calibration data and the set X-ray beam thickness. 
     
     
       6. An X-ray CT scanner, comprising:
 an X-ray tube configured to emit X-rays; 
 an X-ray detector having a plurality of detecting elements and configured to detect X-rays transmitted through a subject; 
 a scanogram generating unit configured to generate scanogram data based on an output of the X-ray detector; 
 an image reconstructing unit configured to reconstruct tomographic data based on an output of the X-ray detector; 
 a display unit; 
 a screen generating unit configured to generate data of an X-ray beam thickness setting support screen, which is to be displayed on the display unit, the X-ray beam thickness setting support screen including the scanogram and a frame including both ends of an X-ray beam obtained in accordance with a thickness of the X-ray beam arranged on the scanogram; 
 a manipulating unit configured to allow a user to graphically manipulate a size of the frame so as to set the thickness of the X-ray beam to an arbitrary integral multiple of a pitch of the detecting elements; and 
 a control unit configured to generate a calibration data file used to correct projection data obtained using the set X-ray beam thickness, from stored calibration data corresponding to predetermined X-ray beam thicknesses other than the set X-ray beam thickness. 
 
     
     
       7. The X-ray CT scanner of  claim 6 , wherein the display unit is configured to display, on the scanogram, information regarding a scanning range covered by a helical scan. 
     
     
       8. The X-ray CT scanner of  claim 6 , wherein the display unit is configured to display a cursor indicating a center of an X-ray beam and a cursor indicating ends of an X-ray beam.